Clinical Significance of Altered Vascular Morphology and Function in Normotension

PURPOSE OF REVIEW

To review current literature examining the presence of subclinical micro- and macrovascular alterations in normotensive individuals and their clinical significance in terms of hypertension prediction. Emphasis is placed on alterations that can be detected in peripheral vascular beds using non-invasive, easily applicable methodology, as these are in general easier to capture and evaluate in clinical practice compared to more complex invasive or functional tests.

RECENT FINDINGS

Arterial stiffness, increased carotid intima-media thickness, and altered retinal microvascular diameters predict the progression from the normotensive to the hypertensive state. By contrast, there is substantial lack of relevant prospective studies for skin microvascular alterations. Although conclusions regarding causality cannot be safely deduced from available studies, detection of morphological and functional vascular alterations in normotensive individuals emerges as a sensitive indicator of progression to hypertension and hence increased CVD risk. An increasing amount of evidence suggests that early detection of subclinical micro- and macrovascular alterations would be clinically useful for the early identification of individuals at high risk for future hypertension onset. Methodological issues and gaps in knowledge need to be addressed before detection of such changes could guide the development of strategies to prevent new-onset hypertension in normotensive individuals.

MicroRNAs in aldosterone production and action

Aldosterone is a cardiovascular hormone with a key role in blood pressure regulation, among other processes, mediated through its targeting of the mineralocorticoid receptor in the renal tubule and selected other tissues. Its secretion from the adrenal gland is a highly controlled process subject to regulatory influence from the renin-angiotensin system and the hypothalamic-pituitary-adrenal axis. MicroRNAs are small endogenous non-coding RNA molecules capable of regulating gene expression post-transcriptionally through stimulation of mRNA degradation or suppression of translation. Several studies have now identified that microRNA levels are changed in cases of aldosterone dysregulation and that microRNAs are capable of regulating the expression of various genes involved in aldosterone production and action. In this article we summarise the major studies concerning this topic. We also discuss the potential role for circulating microRNAs as diagnostic biomarkers for primary aldosteronism, a highly treatable form of secondary hypertension, which would be highly desirable given the current underdiagnosis of this condition.

Mineralocorticoid receptor signaling is implicated in carfilzomib-induced increase in blood pressure

Introduction

Carfilzomib (Cfz), an irreversible proteasome inhibitor, is a first line antineoplastic agent indicated for relapsed/refractory multiple myeloma, with its clinical use being hampered by cardiovascular adverse effects. Hypertension, is the most common cardiovascular side effect of Cfz, remaining of unknown pathogenicity.

Purpose

Considering that management of Cfz-related hypertension remains an unmet clinical need and that renal function plays a pivotal role in blood pressure regulation we sought to investigate the renal contribution in Cfz-induced hypertension.

Methods

We have previously established a translational model of Cfz-induced cardiomyopathy, based on clinically applicable dose regimens and we have concluded that two and four dose protocols successfully resemble the clinical observations in vivo. Herein, sixty C57Bl/6 male mice (12–14 weeks old) were randomized to: 1. Two doses Protocol: i. Control (N/S 0.9%), ii. Cfz (8mg/kg) for two consecutive days; and 2. Four doses Protocol: i. Control (N/S 0.9%), ii. Cfz (8mg/kg) for seven days intraperitoneally. Systolic (SBP) and diastolic blood pressure (DBP) were measured by tail cuffs; the latter protocol was repeated and urine collection was performed via metabolic cages studies. Renal samples were collected for histological, proteomic, metabolomic and molecular signaling analyses. Finally, eplerenone, a mineralocorticoid receptor (MR) blocker, was orally co-administered with Cfz to the mice daily (165 mg/kg) in the four doses protocol.

Results

Cfz increased SBP only in the four doses protocol (78.50±2.05 vs 68.20±0.73 in the Control group, **P<0.01). Histological evaluation of the kidneys revealed a juxtaglomerular apparatus hyperplasia (JAH) in the same dose regimen. Proteomic analysis presented that metabolic and transport of small molecules pathways were differentially regulated in the Cfz treated murine kidneys. Metabolomic analysis revealed an increase in urea cycle metabolites (L-Alanine, L-Glutamine, glutamate, aspartate) and taurine content in the kidneys. Additionally, mice presented decreased diuresis without any differences in other metabolic parameters. In parallel an upregulation of β-ENaC expression and activation of MR/SGK-1 signaling in the kidneys was observed, indicating that Cfz activates MR signaling. Co-administration of eplerenone and Cfz, restored diuresis, decreased SBP and inhibited MR/SGK-1 signaling in the kidneys.

Conclusions

Activation of MR signaling by Cfz in the kidneys orchestrates renal water/salt retention and drives an increase in blood pressure in vivo. Histological and metabolomic analyses present that Cfz induces an acute kidney injury and a tonicity increase. Eplerenone reversed Cfz-induced blood pressure increase and restored diuresis by inhibiting MR/SGK-1 signaling. Therefore, MR blockade emerges as a potent therapeutic approach against Cfz-related cardiovascular adverse events.

Funding Acknowledgement

Type of funding sources: None.